This invention relates generally to a novel method of enhancing the visual or instrumental identification of dentin, or tooth tissue, by applying a fluorescing agent to a cut tooth, cut dental restorative material or dentin surface.
The use of aesthetic (tooth colored) restorative materials in the practice of dentistry has grown tremendously in recent years. The products comprising this type of restoration include porcelain, resin- and ionomer-based materials. Human teeth have a natural fluorescence and manufacturers have purposefully added fluorescing agents to restorative materials so that the restorations will not be distinguishable from the natural conditions upon exposure to black light, ultraviolet energy (UV).
A problem facing the restorative dentist is the complete removal of existing aesthetic-based restorative materials during their replacement due to restoration failure or some other reason. The difficulty in this task is the identification of the point at which old, aesthetic restorative material has been completely removed, and fresh tooth structure has been exposed. The profession has decided to eliminate the use of introral ultraviolet radiation. Previously, UV radiation was specifically used to cause the photo-polymerization of the first generation of radiant-polymerized, direct-placed dental restorative materials. Potential eye problems resulting from low dosages of UV radiation over a long-term to both the clinician and staff as well as the possibility of inducing mutations in the patient""s oral microflora resulted in the use of energy only within the visible spectrum. Thus, energy associated with the visible spectrum is now used to supply the radiation necessary to cause radiant cure of resin-based, aesthetic restorative materials. Current technology utilizes a photo-active agent (typically camphorquinone (CQ)), which has its absorbance maximum between 400 and 500 nm blue light, to provide free radicals necessary for introral polymerization. The spectral absorbance of CQ is provided in FIG. 1.
In order to accommodate for the specific needs of a blue light photoinitiator, the curing light output is filtered to eliminate heat-causing infrared energy, and to limit the bandpass region of visible light between 400 and 500 nm. The absorbance profile of a typical bandpass filter of a dental light curing unit is seen in FIG. 2.
Overlying FIGS. 1 and 2 provides an indication of the restriction of energy emitted from a typical dental photo-curing unit and its relationship to the absorption spectrum of a typical photoinitiator, CQ (FIG. 3).
U.S. Pat. No. 5,102,461 (hereinafter ""461) teaches adding a fluorescent agent to a dental material composition, such that upon application of radiant energy of an appropriate wavelength, the fluorescent agent in the dental material emits fluorescence, which permits visual distinction of the material from the tooth structure.
U.S. Pat. No. 5,269,682 (hereinafter ""682) teaches a method of identifying and removing orthodontic bonding adhesive utilizing a fluorescing agent in the bonding agent composition which attaches an orthodontic bracket to the enamel surface of a tooth. Upon removal of the bracket, distinction between the enamel and unremoved bonding resin is aided by the use of the fluorescence in the bonding agent.
The fluorescent agent in this invention is different from ""461, in that ""461 does not disclose fluorescein fluorescing agents and incorporates the fluorescent agent into a dental material. Furthermore, it is not intended that the fluorescing agent herein is added to a bonding composition as in ""682, but is mixed with a transferring agent and applied directly to cut tooth or dentin to aid in distinguishing between cut tooth or dentin and enamel during the removal of existing aesthetic based restorative materials.
The above-mentioned problem of completely removing existing aesthetic-based restorative material is overcome by providing a fluorescing agent which will aid in visually or instrumentally detecting the presence of dentin.
In one embodiment, the invention provides a method of topically applying a fluorescing agent to a cut tooth or restoration surface having an existing aesthetic restoration comprising the steps of:
a) topically applying a composition consisting essentially of a fluorescing agent to a cut tooth or restoration surface in an effective amount to provide adequate detection of emitted radiation;
b) irradiating the cut tooth or restoration surface with a light source emitting a wavelength in the visible spectrum of about 380 to about 700 nm; and
c) visually or instrumentally identifying the fluorescing agent by observing emitted fluorescence at a wavelength of lower energy than the excitation energy to distinguish between dentin and existing restoration material and/or enamel on the cut tooth or restoration surface, wherein the fluorescing agent bonds/binds to dentin in preference to enamel or to the aesthetic restoration material.
In another embodiment, the invention provides a method of topically applying a fluorescing agent to a cut tooth surface free of existing aesthetic restoration comprising the steps of:
a) topically applying a composition consisting essentially of a fluorescing agent to a cut tooth surface in an effective amount to provide adequate detection of emitted radiation;
b) irradiating the cut tooth surface with a light source emitting a wavelength in the visible spectrum of about 380 to about 700 nm; and
c) visually or instrumentally identifying the fluorescing agent by observing emitted fluorescence, at a wavelength of lower energy than the excitation energy to distinguish between dentin and enamel on the cut tooth surface, wherein the fluorescing agent bonds/binds to dentin in preference to enamel.
In another embodiment, the invention provides a method of topically applying a fluorescing agent to a cut tooth or restoration surface of an existing aesthetic restoration comprising the steps of:
a) topically applying a fluorescing material consisting essentially of phosphate buffered to pH 7 saline solution of fluorescein sodium salt to a cut tooth or restoration surface in an effective amount to provide adequate detection of emitted radiation;
b) irradiating the cut tooth or restoration surface with a light source emitting a wavelength in the visible spectrum of about 380 to about 700 nm; and
c) visually or instrumentally identifying the fluorescing agent by observing emitted fluorescence at a wavelength of lower energy than the excitation energy to distinguish between dentin and existing aesthetic restoration material and/or enamel on the cut tooth or restoration surface, wherein the topically applied fuorescein sodium salt solution bonds or binds to the dentin in preference to enamel or to the aesthetic restoration material.
In another embodiment, the invention provides a method of topically applying a fluorescing agent to a cut tooth surface free of existing aesthetic restoration comprising the steps of:
a) topically applying a fluorescing material consisting essentially of phosphate buffered to pH7 saline solution of fluorescein sodium salt to a cut tooth surface in an effective amount to provide adequate detection of emitted radiation;
b) irradiating the cut tooth surface with a light source emitting a wavelength in the visible spectrum of about 380 to about 700 nm; and
c) visually or instrumentally identifying the fluorescing agent by observing emitted fluorescence at a wavelength of lower energy than the excitation energy to distinguish between dentin and/or enamel on the cut tooth surface, wherein the fluorescing agent bonds or binds to dentin in preference to enamel.
In another embodiment, the invention provides a topical composition for applying to a cut tooth or restoration surface consisting essentially of a fluorescing agent and a transferring agent.
In another embodiment, the invention provides a topical composition for applying to a cut tooth or restoration surface consisting essentially of a sodium salt of fluorescein and a phosphate buffered saline buffered to pH 7.
Additional advantages of the invention will be set fourth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.
The accompanying drawings which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description, serve to explain the principles of the invention.